Medical devices, including implantable medical devices (IMDs), may be used to treat a variety of medical conditions. Medical electrical stimulation devices, for example, may deliver electrical stimulation therapy to a patient via external or implanted electrodes. Electrical stimulation therapy may include stimulation of nerve, muscle, the brain, or other tissue within a patient. In some examples, an electrical stimulation device is fully implanted within the patient. For example, an implantable electrical stimulation device may include an implantable electrical stimulation generator and one or more implantable leads carrying electrodes. Alternatively, the electrical stimulation device may comprise a leadless stimulator in which electrodes are carried on housing of the device. In other examples, implantable electrodes may be coupled to an external electrical stimulation generator via one or more percutaneous leads and/or lead extensions.
Medical electrical stimulation devices have been proposed for use to relieve a variety of symptoms or conditions such as chronic pain, tremor, Parkinson's disease, depression, epilepsy, migraines, urinary or fecal incontinence, pelvic pain, sexual dysfunction, obesity, and gastroparesis. An electrical stimulation device may be configured to deliver electrical stimulation therapy via leads that include electrodes implantable proximate to the spinal cord, pelvic nerves, gastrointestinal organs, peripheral nerves, or within the brain of a patient. Stimulation proximate the spinal cord, within the brain, and proximate peripheral nerves are often referred to as spinal cord stimulation (SCS), deep brain stimulation (DBS), and peripheral nerve stimulation (PNS), respectively.